105 lines
4.2 KiB
Python
Executable File
105 lines
4.2 KiB
Python
Executable File
#!/usr/bin/env python
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#
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# This work is licensed under the Creative Attribution-NonCommercial-ShareAlike
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# 3.0 Unported License.To view a copy of this license, visit
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# http://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to
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# Creative Commons, 444 Castro Street, Suite 900, Mountain View,
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# California, 94041, USA.
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from __future__ import print_function
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from bitarray import bitarray
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# Does anybody read this stuff? There's a PEP somewhere that says I should do this.
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__author__ = 'Cortney T. Buffington, N0MJS'
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__copyright__ = 'Copyright (c) 2016 Cortney T. Buffington, N0MJS and the K0USY Group'
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__credits__ = 'Jonathan Naylor, G4KLX; Ian Wraith'
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__license__ = 'Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported'
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__maintainer__ = 'Cort Buffington, N0MJS'
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__email__ = 'n0mjs@me.com'
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#------------------------------------------------------------------------------
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# BPTC(196,96) Decoding routings
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#------------------------------------------------------------------------------
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mod_181_index = (
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0, 181, 166, 151, 136, 121, 106, 91, 76, 61, 46, 31, 16, 1, 182, 167, 152, 137,
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122, 107, 92, 77, 62, 47, 32, 17, 2, 183, 168, 153, 138, 123, 108, 93, 78, 63,
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48, 33, 18, 3, 184, 169, 154, 139, 124, 109, 94, 79, 64, 49, 34, 19, 4, 185, 170,
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155, 140, 125, 110, 95, 80, 65, 50, 35, 20, 5, 186, 171, 156, 141, 126, 111, 96,
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81, 66, 51, 36, 21, 6, 187, 172, 157, 142, 127, 112, 97, 82, 67, 52, 37, 22, 7,
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188, 173, 158, 143, 128, 113, 98, 83, 68, 53, 38, 23, 8, 189, 174, 159, 144, 129,
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114, 99, 84, 69, 54, 39, 24, 9, 190, 175, 160, 145, 130, 115, 100, 85, 70, 55, 40,
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25, 10, 191, 176, 161, 146, 131, 116, 101, 86, 71, 56, 41, 26, 11, 192, 177, 162,
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147, 132, 117, 102, 87, 72, 57, 42, 27, 12, 193, 178, 163, 148, 133, 118, 103, 88,
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73, 58, 43, 28, 13, 194, 179, 164, 149, 134, 119, 104, 89, 74, 59, 44, 29, 14,
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195, 180, 165, 150, 135, 120, 105, 90, 75, 60, 45, 30, 15)
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# Converts a DMR frame using 98-68-98 (info-sync/EMB-info) into 196 bit array
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def dec_get_binary_19696(_data):
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_bits = bitarray(endian='big')
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_bits.frombytes(_data)
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return _bits[:98] + _bits[-98:]
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# Applies interleave indecies de-interleave 196 bit array
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def dec_deinterleave_19696(_data):
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deint = bitarray(196)
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for index in xrange(196):
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deint[index] = _data[mod_181_index[index]] # the real math is slower: deint[index] = _data[(index * 181) % 196]
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return deint
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# Applies BTPC error detection/correction routines (INCOMPLETE)
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def dec_error_check_19696(_data):
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checked = bitarray(196)
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# Returns useable LC data - 9 bytes info + 3 bytes RS(12,9) ECC
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def dec_get_data_19696(_data):
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databits = _data[4:12]+_data[16:27]+_data[31:42]+_data[46:57]+_data[61:72]+_data[76:87]+_data[91:102]+_data[106:117]+_data[121:132]
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return databits.tobytes()
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#------------------------------------------------------------------------------
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# BPTC(196,96) Decoding routings
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#------------------------------------------------------------------------------
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# not yet implemented
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#------------------------------------------------------------------------------
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# Used to execute the module directly to run built-in tests
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#------------------------------------------------------------------------------
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if __name__ == '__main__':
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from binascii import b2a_hex as h
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from time import time
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# Validation Example
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data = '\x44\x4d\x52\x44\x00\x2f\x9b\xe5\x00\x0c\x30\x00\x04\xc2\xc4\xa1\xa1\x99\x48\x6e\x2b\x60\x04\x10\x1f\x84\x2d\xd0\x0d\xf0\x7d\x41\x04\x6d\xff\x57\xd7\x5d\xf5\xde\x30\x15\x2e\x20\x70\xb2\x0f\x80\x3f\x88\xc6\x95\xe2\x00\x00'
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data = data[20:53]
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t0 = time()
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bin_data = dec_get_binary_19696(data)
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deint_data = dec_deinterleave_19696(bin_data)
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#err_corrected = dec_error_check_19696(deint_data)
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ext_data = dec_get_data_19696(deint_data)
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t1 = time()
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print('TIME: ', t1-t0, '\n')
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print('original 33 byte data block:')
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print(h(data))
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print(len(data), 'bytes')
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print()
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print('binary data (discarding sync)')
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print(len(bin_data), 'bits')
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print(bin_data)
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print()
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print('deinterleaved binary data')
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print(len(deint_data), 'bits')
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print(deint_data)
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print(h(deint_data.tobytes()))
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print()
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print('decoded hex data')
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print(len(ext_data), 'bytes')
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print(h(ext_data)) |